The invention relates to a laryngoscope comprising a handle, a spatula arranged substantially transverse to said handle, and a coupling, wherein said spatula is detachably fixed to said handle by means of said coupling.
The invention relates specifically to such a laryngoscope further comprising an illumination light waveguide and an image waveguide, both of which being attached to said spatula, wherein said illumination light waveguide comprises a proximal end having an illumination light entry opening, and wherein said image waveguide comprises a proximal end having an image exit opening, wherein said illumination light entry opening and said image exit opening are arranged in the area of said coupling, and wherein said handle comprises, in the area of said coupling, an illumination light exit opening and an image entry opening which allow for an illumination light signal to couple from said handle into said illumination light waveguide, and for an image signal to couple out of said image waveguide.
A laryngoscope of that kind is generally known from EP 0 901 772 A1.
The image waveguide of the known laryngoscope, which might be designated as video-laryngoscope, serves for grabbing an image in the area of the distal end of said spatula, i.e. from a throat area of a patient, and for transmitting said image to an image displaying unit. The image displaying unit might be attached to the handle, but this is not necessary. In any case, however, the grabbed image signal has to be transferred over the separable coupling. This is achieved by coupling the image signal from the image waveguide arranged on the spatula into the image entry opening of an image grabbing system that is located in the handle.
Coupling an image signal from one image waveguide into another always causes losses in quality. As it has turned out, these losses are the less, the more exact the corresponding openings are aligned with respect to each other.
The laryngoscope known from EP 0 901 772 A1 comprises a catching fastener located in the region of the coupling, and ensuring that the laryngoscope spatula is connectable to an image grabbing unit, which is located in the handle, such that the region of the throat area, which is important for the operating physician, can always be imaged. However, any reduction of losses in quality as mentioned above is not guaranteed by this configuration, since the region which is important for the physician to be observed allows positional displacements in the range of several millimeters, whereas the image transmitting quality is already impaired at relative positional displacements of the two coupling openings in the range of several micrometers. Thus, a reduction of losses in quality requires a substantially higher positional accuracy.
From U.S. Pat. Nos. 5,846,186 and 5,800,344, video-laryngoscopes are known wherein the image waveguide is not led across the coupling, just in contrast to the laryngoscope mentioned at the outset. That is how losses in quality are avoided, since the image waveguide can be made in one piece. These laryngoscopes, however, complicate the handling for the physician due to the cables in the proximal region of the spatula.
It is therefore an object of the present invention to provide a laryngoscope of the type mentioned at the outset which provides for reduced losses in quality during image transfer, and which provides a simple handling at the same time.
This object is achieved with a laryngoscope as mentioned at the outset that comprises a centering element which automatically aligns the image entry opening and the image exit opening precisely to each other.
By means of such a centering element, a given adjustment of the coupling openings is not only fixed, but beyond that the absolute position of the coupling openings with respect to each other is guaranteed, in contrast to a catching fastener. From the technical point of view, displacement of the positions of the coupling openings is not only prevented after putting together the spatula and the handle, but, what is more, in putting together the handle and the spatula, an optimum alignment of the coupling openings is already attained. Thereby, the light entry opening and the light exit opening are always optimally arranged with respect to each other, and losses in quality are minimum when the image signal is coupled over.
Moreover, the laryngoscope according to this invention provides for the same easy handling as the laryngoscope mentioned at the outset. The object is therefore completely achieved.
In an embodiment of the invention, the centering element mechanically aligns said image entry opening and said image exit opening with respect to each other.
This feature provides for a simple and robust handling, in particular when connecting the spatula to the handle.
In a further embodiment, the centering element aligns the image entry opening and the image exit opening both in radial and in axial direction with respect to each other.
This feature is particularly advantageous with respect to the fact that not only a radial displacement of the openings allocated to each other, but also an axial displacement may cause deterioration in image quality. For attaining an optimum image quality, it is therefore advantageous to center the openings allocated to each other in every direction.
In a further embodiment, the centering element fixes said entry and exit openings with a variation in fitting of less than 0.5 mm, preferably less than 0.1 mm.
These dimensions have turned out to be advantageous in practical experiments in order to guarantee a constant image quality even during a rough handling of the laryngoscope, and during force impact, in particular in emergency situations.
In a further embodiment, the centering element comprises at least one cone and a corresponding counter cone, one of which being disposed at said handle and the other one at said spatula.
Such an embodiment has turned out to be particularly advantageous for the centering element, as it is simple and robust on the one hand, and it combines the advantageous features mentioned before on the other.
In a further embodiment, the centering element comprises an electronic image alignment unit.
In particular, an electronic image alignment unit can be realized by arranging an electronic image or frame grabber, e.g. a CCD-chip, in the handle of the laryngoscope, the light-sensitive, active area of which being larger than the area really required. In such a case, the electronic image or frame grabber is capable to catch the image signal transmitted by the image waveguide even, if the adjustment of the image entry and exit openings is not exactly maintained any more. By measures known per se from electronic image processing, the xe2x80x9ctruexe2x80x9d image sector can be extracted then. The feature has the advantage, both if taken alone or in combination with a mechanical alignment element, that the image quality of the laryngoscope according to the invention can be constantly maintained, even if loads and forces are acting.
In a further preferred embodiment of the invention, the image entry opening and the illumination light exit opening are located in different coupling planes that are axially displaced with respect to each other.
This feature has the advantage that scattering of the illumination light signal into the image waveguide is prevented in a simple manner, whereby the image quality of the inventive laryngoscope is further improved.
In a further preferred embodiment, the coupling is a standard coupling for connecting laryngoscope-spatulas to handles.
In this connection, every coupling is considered as a standard coupling which has become so widespread among laryngoscopes that a considerable number of laryngoscopes operate with this coupling. The feature has the advantage that the spatulas and handles of the laryngoscopes being already in use can alternatively be combined with the spatula and the handle of the inventive laryngoscope, although the image displaying unit might not be used in this case. In an emergency situation, however, there is the possibility to combine any spatula more suitable with respect to its size with the handle of the inventive laryngoscope due to this feature. All in all, the application variety is enlarged due to the features mentioned.
In a further embodiment of the feature mentioned before, the coupling complies with the requirements of International Standard ISO 7376-3.
This standard defines a standard coupling for connecting spatulas and handles of laryngoscopes. Accordingly, numerous laryngoscopes operate with this standard coupling, and they benefit from the combination possibilities discussed before.
In a further embodiment of the features mentioned before, the coupling comprises, at the proximal end of the image waveguide, a coupling area which is located outside of the coupling area defined by International Standard ISO 7376-3.
Alternatively, it is basically feasible to integrate the proximal end of the image waveguide in the coupling within the dimensions determined by standard ISO 7376-3. In contrast thereto, the feature has the advantage that the region defined by the standard need not be modified, which considerably facilitates compliance with this standard. In addition, due to this feature, a second coupling region is provided which improves the stability and the support of the coupling. This is particularly advantageous with respect to the accuracy in fitting which has to be observed in positioning the entry and exit openings allocated to each other.
In a further embodiment of the invention, the laryngoscope comprises an image displaying unit located at the handle in order to display a grabbed image.
This feature makes the inventive laryngoscope autonomous, i.e. it may be used independently of an external monitor or any other external devices. In that way, handling and expenditure, in particular with respect to emergency situations, is considerably facilitated.
In a further embodiment of the feature mentioned before, the image displaying unit is located on a side of the handle facing away from the distal end of the spatula.
This feature has the advantage that the operating physician can observe the image supplied by the image displaying unit virtually from behind, i.e. from the reverse side of the laryngoscope. This is particularly favorable, since the operating physician thus can quickly switch between the image supplied by the image displaying unit and a direct glance into the throat area of the patient, without having to turn his head a lot.
In a further embodiment, the image displaying unit is rotatable around a longitudinal axis of the handle.
This feature has the advantage that the operating physician can easily adjust the alignment of the image displaying unit to his needs. Moreover, a rotation of the image displaying unit about the longitudinal axis of the handle can be realized in a more robust way than a rotation about an axis that is orthogonal to the longitudinal axis of the handle. The laryngoscope of this embodiment is therefore very robust, in spite of the additional possibility of adjusting.
In a further embodiment, the image displaying unit can be tilted with respect to the longitudinal axis of the handle.
This feature also has the advantage that the operating physician can adjust the alignment of the image displaying unit to his needs while using the laryngoscope.
In a further embodiment, the image displaying unit can be separated from the handle.
This feature has the advantage that the image displaying unit can easily be exchanged in case of damage. Another advantage is that the operating physician may remove the image displaying unit from the handle, if he does not need it any longer for the treatment of a patient. In this case, the inventive laryngoscope corresponds to any common laryngoscope without an image displaying unit with respect to its dimensions and its handling.
In a further embodiment, at least a part of the spatula is made of a light guiding material which forms the illumination light waveguide.
This feature has the advantage that additional optical fibers for the illumination light waveguides might be omitted. In that way, robustness of the laryngoscope can be further improved, while production costs can be saved at the same time. In addition, a light exit for illuminating the throat area can be arranged in a simple way at the distal end of the spatula, without the need to change the function-dependent shape of the spatula.
In a further embodiment, the laryngoscope comprises at least two image waveguides and two image grabbing units.
This feature has the advantage that a stereoscopic and, thus, a spatial image can be achieved which further facilitates the orientation for the operating physician when intubating a patient.
In a further embodiment, a gas sensor for measuring parameters of a gas mixture is arranged at the distal end of the spatula.
The gas sensor preferably serves for determining the oxygen content and/or the CO2 content. The measure is particularly advantageous when the laryngoscope is used in emergency situations for intubating an asphyxiating patient. In such a situation, the amount of oxygen can be determined in the region of the trachea entrance in a simple manner.
In a further embodiment of the feature mentioned before, the gas sensor is connected to an evaluation unit arranged in the handle.
This feature has the advantage that the relatively delicate evaluation unit is protected in the laryngoscope. Furthermore, the laryngoscope provides for the possibility to use the signals of the gas sensor without external devices.
It is to be understood that the features mentioned above and those to be explained below are not only applicable in the given combinations, but may also be used in different combinations or taken alone without departing from the scope of the present invention.